Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <iostream>
#include <queue>
#include <utility>

using namespace std;

int H,W;
char m[50][50];
int c[50][50];
queue<pair<int,int> > q;
int dif[5] = {0,-1,0,1,0};

int main(){
  int count = 0;
  cin >> H >> W;
  for(int i=0;i<H;i++){
    for(int j=0;j<W;j++){
      cin >> m[i][j];
      c[i][j] = -1;
      if(m[i][j] == '.') count++;
    }
  }
  c[0][0] = 1;
  q.push(make_pair(0,0));
  while(!q.empty()){
    int x = q.front().first;
    int y = q.front().second;
    q.pop();
    for(int i=0;i<4;i++){
      if(x+dif[i] < 0 || y+dif[i+1] < 0) continue;
      if(x+dif[i] >= H || y+dif[i+1] >= W) continue;
      int X = x+dif[i];
      int Y = y+dif[i+1];
      if(m[X][Y] == '#' || c[X][Y] != -1) continue;
      c[X][Y] = c[x][y] + 1;
      q.push(make_pair(X,Y));
    }
  }
  if(c[H-1][W-1] == -1){
    cout << -1 << endl;
    return 0;
  }
  cout << count - c[H-1][W-1] << endl;
  return 0;
}